Boundary mode coupled inductor boost power converter

Abstract

Methods, systems, and devices are described for using coupled inductor boost circuits to operate in a zero current switching (ZCS) and/or a zero voltage switching (ZVS) boundary mode. Some embodiments include a coupled inductor boost circuit that can substantially eliminate rectifier reverse recovery effects without using a high side primary switch and a high side primary switch driver. Other embodiments include a coupled inductor boost circuit that can achieve substantially zero voltage switching. ZCS and ZVS modes may be effectuated using control techniques. For example, a magnetizing current may be sensed or otherwise represented, and a signal may be generated accordingly for controlling switching of the controller.

1 . A power converter system, comprising:
 a coupled inductor power converter subsystem, comprising:
 a transformer module having a primary side and a secondary side electromagnetically coupled with the primary side, the transformer module configured to produce second energy on the secondary side as a function of first energy developed on the primary side of the transformer module; 
 a primary power module, coupled with the primary side of the transformer module and configured to control the first energy developed on the primary side of the transformer module at least according to input power received from a power source; and 
 a secondary power module, coupled with the secondary side of the transformer module and configured to deliver at least some of the second energy from the secondary side of the transformer module to an output; and 
   a control subsystem, coupled with the primary power module and configured to further control the first energy developed on the primary side of the transformer module according to the second energy produced on the secondary side of the transformer module.   
     
     
         2 . The power converter system of  claim 1 , wherein the control subsystem is configured to drive the coupled inductor power converter subsystem to operate in a substantially zero current switching mode by allowing a magnetizing current developed in the transformer module to drop substantially to zero during each operating cycle of the coupled inductor power converter subsystem. 
     
     
         3 . The power converter system of  claim 2 , wherein:
 the primary power module is configured to operate in an OFF operating state and in an ON operating state, and to transition the primary power module from the OFF operating state to the ON operating state when a magnetic energy of the transformer module drops substantially to zero.   
     
     
         4 . The power converter system of  claim 1 , wherein the control subsystem is configured to drive the coupled inductor power converter subsystem to operate in a substantially zero voltage switching mode by allowing a magnetizing current developed in the transformer module to fall sufficiently below zero during each operating cycle of the coupled inductor power converter subsystem to produce a reversed magnetizing current, such that the reversed magnetizing current is sufficient to switch the primary power module using a substantially zero switching voltage. 
     
     
         5 . The power converter system of  claim 4 , wherein:
 the primary power module is configured to operate in an OFF operating state for an OFF duration and in an ON operating state for an ON duration, such that a magnetic energy develops on the transformer module during the OFF duration in an amount sufficient to fully discharge an intrinsic output capacitance of the primary power module during a transition of the primary power module from the OFF operating state to the ON operating state.   
     
     
         6 . The power converter system of  claim 1 , wherein the primary power module comprises a first switching sub-module, electrically coupled with the power source and the primary side of the transformer module, and configured to control flow of current from the power source to the primary side of the transformer module so as to control the first energy developed on the primary side of the transformer module. 
     
     
         7 . The power converter system of  claim 6 , wherein the secondary power module comprises:
 a second switching sub-module electrically coupled with a first terminal of the output and configured to switch substantially in synchronization with the first switching sub-module; and   a third switching sub-module electrically coupled with a second terminal of the output and configured to switch substantially in anti-synchronization with the first switching sub-module.   
     
     
         8 . The power converter system of  claim 6 , wherein:
 the transformer module is configured to produce a magnetizing current in a coupled inductor, the magnetizing current having an AC component and a DC component, the AC component having a magnitude that is at least twice that of the DC component; and   the coupled inductor power converter subsystem is configured such that a magnetizing energy corresponding to the magnetizing current contributes to discharging an intrinsic output capacitance of the first switching sub-module during a turn-on switching transition of the first switching sub-module.   
     
     
         9 . The power converter system of  claim 1 , wherein the primary power module and the secondary power module are configured to operate in a first operating state and a second operating state, such that at least some of the second energy from the secondary side of the transformer module is delivered to the output during both the first operating state and a second operating state. 
     
     
         10 . The power converter system of  claim 1 , wherein the transformer module comprises:
 a coupled inductor having a primary winding at the primary side, a secondary winding at the secondary side, and a magnetic core structure between the primary side and the secondary side, the primary winding and the secondary winding configured to be mutually magnetically coupled, and the magnetic core structure configured to store magnetic energy.   
     
     
         11 . The power converter system of  claim 1 , wherein the transformer module comprises:
 a tapped inductor having at least three terminals and configured to manifest a primary winding and a secondary winding at the primary side and the secondary side of the transformer module of the coupled inductor power converter subsystem, respectively.   
     
     
         12 . The power converter system of  claim 1 , wherein the control subsystem comprises:
 a representation module, configured to generate a representation of magnetizing energy produced on the secondary side of the transformer module,   the control subsystem configured to generate a control signal as a function of the representation of the magnetizing energy and to use the control signal to contribute to control the first energy developed on the primary side of the transformer module.   
     
     
         13 . The power converter system of  claim 12 , wherein the representation module comprises:
 a sensor configured to sense the magnetizing energy produced on the secondary side of the transformer module and output a signal as the representation.   
     
     
         14 . A method for power conversion, comprising:
 generating a first signal corresponding to magnetizing energy developed on a secondary side of a transformer in a coupled inductor power converter;   selecting a comparison threshold;   generating a second signal as a function of the first signal and the comparison threshold; and   controlling a primary side of the transformer in the coupled inductor power converter as a function of the second signal such that the coupled inductor power converter operates in an OFF operating state and in an ON operating state during each converter operating cycle, and transitions from the OFF operating state to the ON operating state occur according to the second signal.   
     
     
         15 . The method of  claim 14 , wherein controlling the primary side of the transformer in the coupled inductor power converter as a function of the second signal comprises:
 driving a transition of the coupled inductor power converter from the OFF operating state to the ON operating state when a magnetic energy of the transformer drops substantially to zero.   
     
     
         16 . The method of  claim 14 , wherein the coupled inductor power converter is configured such that a magnetic energy develops on the transformer during the OFF operating state in an amount sufficient to fully discharge an intrinsic output capacitance of a switching component on the primary side during a transition from the OFF operating state to the ON operating state. 
     
     
         17 . The method of  claim 14 , wherein generating the first signal corresponding to the magnetizing energy developed on the secondary side of the transformer in the coupled inductor power converter comprises:
 sensing a magnetizing current in the transformer,   the first signal generated as a function of the sensed magnetizing current.   
     
     
         18 . The method of  claim 14 , wherein generating the first signal corresponding to the magnetizing energy developed on the secondary side of the transformer in the coupled inductor power converter comprises:
 providing a modeling circuit substantially electrically isolated from the secondary side of the transformer and configured to generate an output corresponding to the magnetizing energy developed on the secondary side of the transformer in the coupled inductor power converter; and   generating the first signal as a function of the output of the modeling circuit.   
     
     
         19 . A power converter system, comprising:
 a coupled inductor power converter subsystem having a transformer, a primary side of the transformer being configured to be driven by a primary power module, the primary power module comprising a means for switching configured to control first energy developed on the primary side of the transformer;   means for generating a representation of second energy developed on a secondary side of the transformer; and   means for controlling the means for switching so as to further control the first energy developed at the primary side of the transformer module according to the second energy developed at the secondary side of the transformer.   
     
     
         20 . The power converter system of  claim 19 , wherein the means for controlling the means for switching is configured to drive the coupled inductor power converter subsystem to operate in a substantially zero current switching mode by allowing a magnetizing current developed in the transformer module to drop substantially to zero during each operating cycle of the coupled inductor power converter subsystem. 
     
     
         21 . The power converter system of  claim 19 , wherein the means for controlling the means for switching is configured to drive the coupled inductor power converter subsystem to operate in a substantially zero voltage switching mode by allowing a magnetizing current developed in the transformer module to fall sufficiently below zero during each operating cycle of the coupled inductor power converter subsystem to produce a reversed magnetizing current, such that the reversed magnetizing current is sufficient to drive the means for switching into an ON switching state with substantially zero switching voltage.